M41TC8025CMC7F datasheet(25/41 Pages) STMICROELECTRONICS

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M41TC8025

Operation

2.8

Alarm interrupt function

The alarm interrupt function generates an alarm at the condition set in the alarm registers in

08h to 0Ah. Once the current clock and calendar match the alarm condition, the alarm

function is activated. The flag bit (AF) will be set to 1 to indicate the alarm event and the IRQ

pin will be pulled low if enabled (bit AIE=1). There is no auto clear of either the IRQ pin or

the flag bit.

The alarm interrupt function related registers are given in Table 19.

Note:

All the alarm interrupt function related register bits are marked in bold.

2.8.1

Related registers

Registers from 01h to 04h are the current clock and calendar registers and are described in

detail in Section 2.4: Clock and calendar.

Registers from 08h to 0Ah are the alarm condition setting for minutes, hours and day/date.

The MSB of each register is the alarm masking bit AM_M, AM_H and AM_D. If AM_x=0, the

alarm occurs when the alarm register setting matches the corresponding current clock and

calendar register values. If AM_x=1, this alarm register value will not be compared with the

corresponding clock and calendar value.

(Week-alarm/Day-alarm) bit in register 0Dh. If WADA=0, day-of-week is selected. If

WADA=1, date (day of month) is selected.

The possible values of the alarm minutes register in 08h are in BCD format of "00", "01",

"02" and up to "59".

The possible values of the alarm hours register in 09h are in BCD format of "00", "01", "02"

and up to "23".

In the alarm day-of-week register in 0Ah, one bit represents one day from bit 0 to bit 6,

which is the same definition as the calendar Day-of-week register 03h. The only difference

Table 19. Alarm interrupt related register bits

Address

Function

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

01h

Minutes

842

02h

Hours

03h

Day-of-week

321

04h

Date (day of month)

08h

Alarm minutes

AM_M

09h

Alarm hours

AM_H

0Ah

Alarm day

AM_D

4321

Alarm date

0Dh

Extension register

TEST

WADA

USEL

FSEL1

FSEL0

TSEL1

TSEL0

0Eh

Flag register

VLF

VDET

0Fh

Control register

CSEL1

CSEL0

UIE

TIE

AIE

RESET

Obsolete

Product(s)

- Obsolete

Product(s)

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